Tasmania's Oysters Are in Danger of Being Wiped Out by a Lethal Form of Herpes

Eat all the Tassie oysters you can because in a few years. Soon, they could be all-but-extinct, warn experts.

Pacific Oyster Mortality Syndrome (POMS) causes lesions, inflammation, and larvae to stop swimming and feeding, killing close to 100 percent of infected animals within eight to ten days. With very little information available about factors responsible for the outbreaks, how the disease is spread is still not clear, say Oysters Australia. "It is theorized that international spread of the disease may have taken place in association with biofouling (e.g. oysters) attached to the hulls of ships," report the organisation.

The disease, known scientifically as Ostreid herpesvirus-1 microvariant, is thought to be brought on by environmental or handling stress and is worsened by crowding and high water temperatures; a condition symptomatic of climate change manifest in waters off Tasmania's east coast this summer.

Since 2007, the virus, which is not known to be dangerous to humans, has affected Pacific oysters in Europe, New Zealand, and Australia, devastating farms around Sydney, as well as the Georges and Hawkesbury rivers. Affecting Tasmania's major hatcheries, which supply 90 percent of seed to the Australian industry, POMS could ravage Australia's population of pacific oysters if not adequately managed, say experts.

"Few growers are going to be able to get seed in the near future. This is all aside from the fact that where the virus occurs, it will slaughter 90 percent of the standing crop, adults and seed included. It will be a rough, rough patch of years coming up and many will go bust," said Standish Allen, a professor of marine science, aquaculture genetics, and breeding technology, who also invented the popular non-spawning "triploid" oyster, which can be consumed throughout the year.

"There needs to be some bold decisive action on this to avoid losing the industry altogether. But it will still take years," he said. An oyster takes roughly two years to grow.

Affecting seven commercial growing areas in Tasmania, the current outbreak has killed up to 80 percent of stock on some farms, resulted in the layoff of many employees, and severely restricted the movement of any oysters within and outside the state, leading Tasmania's industry leaders to call on the Australian government to help fund strategies like the breeding of POMS-resistant oysters and immunisation trials currently being carried out in NSW.

While the majority of oysters sold in Australia are of the Pacific variety, POMS does not affect Sydney Rock Oysters or Angasi, also sold in NSW, QLD, and in small amounts in WA.

With 85 percent of natural reefs already wiped out, oysters are already considered "functionally extinct" given that they play no significant role in the ecosystem. All oysters sold in Australia are farmed.

"If there were wild populations left after the farm animals are dead or eaten, they would likely prevail in a few places," said Allen, adding, that it would be "hard to overcome Mother Nature's resilience."